1. Field
Direct communication between end user terminals is particularly discussed in the context of wireless communication. Techniques, systems, and other technology for providing operation of a direct-to-direct user on a high speed packet access frequency band for cellular mode communication and operation of the direct-to-direct user on a long term evolution direct-to-direct user frequency band for direct-to-direct communication are presented, which may be relevant to wireless mobile devices and high-volume network infrastructure, and related components (chipsets).
2. Description of the Related Art
In the following it is assumed that device-to-device (D2D) communication is available at Long Term Evolution (LTE) cells using an LTE air interface of 3rd Generation Partnership Project (3GPP). When a D2D user is moving from an LTE cell to a High Speed Packet Access (HSPA) cell, the HSPA system may not able to support the D2D communication. The area of LTE deployment may be smaller than that of the HSPA system, especially in the beginning of LTE deployment. So, D2D usage would be expected to be quite low due to the limited deployment of LTE D2D capable evolved Node Bs (eNBs). Furthermore, one challenge may be how to utilize existing infrastructure to assist LTE D2D communication with as minor modifications to the HSPA system as possible.
In many networks, it is expected that the cellular system should operate in the same frequency band as the D2D communication. Then the cellular system is responsible for the resource allocation or division among D2D users and cellular users.